Pumps



L. STERLING Nov. 22, 1966 PUMPS Filed Sept. 5, 1964 United States Patent3,286,644 PUMPS Leslie Sterling, Poole, Dorset, England, assignor toHamworthy Pumps & Compressors Limited, Poole, Dorset, England FiledSept. 3, 1964, Ser. No. 394,133 Claims priority, application GreatBritain, Sept. 18, 1963, 36,703/63 2 Claims. (Cl. 103-128) Thisinvention relates to screw pumps or other pumping machinery, especiallyof the sort in which the normally incoming flow has to be split into twostreams which normally enter into and How through the pumping element,e.g., rotating screws in opposite directions to each other. It is anobject of the invention to provide a pump of increased life and easiermaintenance than known pumps.

It is desirable to have the portion of the walls of the pump casingwhich is in contact with or in close proximity to the screws or otherpumping element replaceable since this forms the wearing area of thepumping chamber. The present invention achieves the foregoing byproviding a casing having an open end, removable means for closing theopen end, a hollow open ended tubular insert constituting a pumpingchamber within the casing spaced at both ends thereof from the ends ofthe casing, intermeshing symmetrical double-ended counter-rotatingscrew-threaded rotors closely fitting in the chamber for pumping a fluidthrough he chamber, first and second opposed lateral extensions integralwith the tubular insert bearing against internal surfaces of the casingfor spacing the pumping chamber laterally from the casing, said casinghaving a first port at one end communicating directly with therespective end of the pumping chamber and a second port laterallydisposed and aligned with said first extension, said first extensionbeing provided with a laterally extending port interconnecting saidpumping chamber and second port, said second extension being providedwith a longitudinally extending passage interconnecting the ends of thecasing so that said first port communicates with both ends of thepumping chamber, said first extension sealing the laterally extendingport from the interior of the casing, and said insert and first andsecond lateral extensions being slidable within the casing whereby theinsert and extensions can be removed bodily from the casing through theopen end thereof upon removal of the removable means.

A counterflow screw pump embodying the invention will now be describedwith reference to the accompanying drawing, in which:

FIGURE 1 is an axial cross section of a screw pump;

FIGURE 2 is a cross section on line II-II of FIGURE 1, the pump rotorsbeing omitted.

The pump, as is usual, includes two or more parallel double-endedmeshing screw threaded rotors 1 on shafts 19 rotating in oppositedirections inside a pumping chamher 2 of figure-8 cross-section as shownin FIGURE 2.

The chamber is formed in an insert 3 which has a tubular body 6 open ateach end to form inlet ports 4 and has a single lateral extensionconstituting an outlet port 5 at its mid point. Integral with thetubular body 6 on the side opposite the outlet port is an arcuatelateral extension 7 defining a passage 9 parallel to the rotors 1.

The pumping chamber insert 3 is disposed inside a main pump casing 10having a generally cylindrical tubular form. The casing is spaced fromthe insert at each end so as to define suction bays 11 communicatingwith the inlet ports 4, and the outlet port 5 of the chambercommunicates with an outlet branch 12 of the casing.

3,286,544 Patented Nov. 22, 1966 The outlet port 5 and the extension 7on the opposite side of the insert fit closely in the casing 10 toprovide a seal between the high and low pressure areas of the maincasmg, 1.e., the suction bays and outlet branch.

1ft single inlet branch 13 is provided at one end of the casing andcommunicates directly with the suction bay 11 at that end of the casing.Fluid can flow from the inlet branch to the other suction bay throughthe passage 9 defined by the extension 7 as shown by the arrows 14 inFIGURE 1. An end of the casing is detachable, so that the pumpingchamber can be removed bodily from the casing.

In the drawing this is shown at the end remote from the inlet branch,the main body of the casing 10 endmg in flanges 15 to which flanges 16of an end piece 17 are attached, for example by bolts 18.

It will be understood that the pump shown is merely exemplary and thatother arrangements are possible. For example the passage 9 could bedefined partly by the wall of the casing instead of being wholly withinthe insert, with the arcuate projection 7 being replaced by one or moresolid projections serving the same function of spacing the body 6 fromthe casing 10. In such a case the inlet branch 13 could be arrangedcentrally.

I claim:

1. A countrflow screw pump including a casing having an open end,removable means for closing the open end, a hollow open ended tubularinsert constituting a pumping chamber within the casing spaced at bothends thereof from the ends of the casing, intermeshing symmetricaldouble-ended counter-rotating screw-threaded rotors closely fitting inthe chamber for pumping a fluid through the chamber, first and secondopposed lateral extensions integral with the tubular insert bearingagainst internal surfaces of the casing for spacing the pumping chamberlaterally from the casing, said casing having a first port at one endcommunicating directly with the respective end of the pumping chamberand a second port laterally disposed and aligned with said firstextension, said first extension being provided with a laterallyextending port interconnecting said pumping chamber and second port,said second extension being provided with a longitudinally extendingpassage interconnecting the ends of the casing so that said first portcommunicates with both ends of the pumping chamber, said first extensionsealing the laterally extending port from the interior of the casing,and said insert and first and second lateral extensions being slidablewithin the casing whereby the insert and extensions can be removedbodily from the casing through the open end thereof upon removal of theremovable means.

2. The counterflow screw pump as claimed in claim 1 in which said firstport is at that end of the casing remote from the open end thereof andsaid second part and laterally extending port are located at themidpoint of the casing and pumping chamber, respectively.

References Cited by the Examiner UNITED STATES PATENTS 1,701,166 2/1929Tiift 103128 2,171,146 8/1939 Montelius 103-128 2,588,888 3/1952 Sennet103-128 2,590,561 3/ 1952 Montelius l03l28 2,640,430 6/1953 Sennet103-128 FOREIGN PATENTS 430,601 6/ 1935 Great Britain.

MARK NEWMAN, Primary Examiner.

WILBUR I. GOODLIN, Examiner.

1. A COUNTERFLOW SCREW PUMP INCLUDING A CASING HAVING AN OPEN END,REMOVABLE MEANS FOR CLOSING THE OPEN END, A HOLLOW OPEN ENDED TUBULARINSERT CONSTITUTING A PUMPING CHAMBER WITHIN THE CASING SPACED AT BOTHENDS THEREOF FROM THE ENDS OF THE CASING, INTERMESHING SYMMETRICALDOUBLE-ENDED COUNTER-ROTATING SCREW-THREADED ROTORS CLOSELY FITTING INTHE CHAMBER FOR PUMPING A FLUID THROUGH THE CHAMBER, FIRST AND SECONDOPPOSED LATERAL EXTENSIONS INTEGRAL WITH THE TUBULAR INSERT BEARINGAGAINST INTERNAL SURFACES OF THE CASING FOR SPACING THE PUMPING CHAMBERLATERALLY FROM THE CASING, SAID CASING HAVING A FIRST PORT AT ONE ENDCOMMUNICATING DIRECTLY WITH THE RESPECTIVE END OF THE PUMPING CHAMBERAND A SECOND PORT LATERALLY DISPOSED AND ALIGNED WITH SAID FIRSTEXTENSION, SAID FIRST EXTENSION BEING PROVIDED WITH A LATERALLYEXTENDING PORT INTERCONNECTING SAID PUMPING CHAMBER AND SECOND PORT,SAID SECOND EXTENSION BEING PROVIDED WITH A LONGITUDINALLY EXTENDINGPASSAGE INTERCONNECTING THE ENDS OF